Enable IAccessible2 for MinGW

MinGW 5.3 is able to compile the IAccessible2 classes. All that is needed
is some way to provide the missing IIDs, which is done via specialization
of a function template (similar to the MinGW's __uuidof operator).

[ChangeLog][Windows][Accessibility] MinGW builds now support IAccessible2.

Change-Id: I218a4b89c81b54aa96f7c743544388631ca9a53e
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

8 files changed, 49 insertions, 38 deletions

diff --git a/src/3rdparty/iaccessible2/generated/x86/ia2_api_all.h b/src/3rdparty/iaccessible2/generated/x86/ia2_api_all.h
index eb3b57b8bd..9e4be75bb9 100644
--- a/src/3rdparty/iaccessible2/generated/x86/ia2_api_all.h
+++ b/src/3rdparty/iaccessible2/generated/x86/ia2_api_all.h
@@ -16,7 +16,9 @@
 */
 /* @@MIDL_FILE_HEADING(  ) */
 
-#pragma warning( disable: 4049 )  /* more than 64k source lines */
+#ifdef _MSC_VER
+#  pragma warning( disable: 4049 )  /* more than 64k source lines */
+#endif
 
 
 /* verify that the <rpcndr.h> version is high enough to compile this file*/
diff --git a/src/3rdparty/iaccessible2/generated/x86/ia2_api_all_i.c b/src/3rdparty/iaccessible2/generated/x86/ia2_api_all_i.c
index c50b3e9a4f..61bb5ee5f7 100644
--- a/src/3rdparty/iaccessible2/generated/x86/ia2_api_all_i.c
+++ b/src/3rdparty/iaccessible2/generated/x86/ia2_api_all_i.c
@@ -18,7 +18,9 @@
 */
 /* @@MIDL_FILE_HEADING(  ) */
 
-#pragma warning( disable: 4049 )  /* more than 64k source lines */
+#ifdef _MSC_VER
+#  pragma warning( disable: 4049 )  /* more than 64k source lines */
+#endif
 
 
 #ifdef __cplusplus
@@ -65,7 +67,7 @@ typedef IID CLSID;
 #define MIDL_DEFINE_GUID(type,name,l,w1,w2,b1,b2,b3,b4,b5,b6,b7,b8) \
         const type name = {l,w1,w2,{b1,b2,b3,b4,b5,b6,b7,b8}}
 
-#endif !_MIDL_USE_GUIDDEF_
+#endif // !_MIDL_USE_GUIDDEF_
 
 MIDL_DEFINE_GUID(IID, IID_IAccessibleRelation,0x7CDF86EE,0xC3DA,0x496a,0xBD,0xA4,0x28,0x1B,0x33,0x6E,0x1F,0xDC);
 
diff --git a/src/plugins/platforms/windows/accessible/accessible.pri b/src/plugins/platforms/windows/accessible/accessible.pri
index 0e3aacc558..557bdfe307 100644
--- a/src/plugins/platforms/windows/accessible/accessible.pri
+++ b/src/plugins/platforms/windows/accessible/accessible.pri
@@ -6,13 +6,14 @@ HEADERS += \
     $$PWD/qwindowsaccessibility.h \
     $$PWD/comutils.h
 
-SOURCES += $$PWD/qwindowsmsaaaccessible.cpp
-HEADERS += $$PWD/qwindowsmsaaaccessible.h
+SOURCES += \
+    $$PWD/qwindowsmsaaaccessible.cpp \
+    $$PWD/iaccessible2.cpp
+
+HEADERS += \
+    $$PWD/qwindowsmsaaaccessible.h \
+    $$PWD/iaccessible2.h
 
-!mingw: {
-    SOURCES += $$PWD/iaccessible2.cpp
-    HEADERS += $$PWD/iaccessible2.h
-    include(../../../../3rdparty/iaccessible2/iaccessible2.pri)
-}
+include(../../../../3rdparty/iaccessible2/iaccessible2.pri)
 
 mingw: LIBS *= -luuid
diff --git a/src/plugins/platforms/windows/accessible/iaccessible2.h b/src/plugins/platforms/windows/accessible/iaccessible2.h
index d5c67f8b51..1597c41160 100644
--- a/src/plugins/platforms/windows/accessible/iaccessible2.h
+++ b/src/plugins/platforms/windows/accessible/iaccessible2.h
@@ -52,6 +52,12 @@
 
 QT_BEGIN_NAMESPACE
 
+#ifdef Q_CC_MINGW
+// MinGW's __uuidof operator does not work for the Accessible2 interfaces
+template <>
+IID qUuidOf<IAccessibleComponent>() { return IID_IAccessibleComponent; }
+#endif // Q_CC_MINGW
+
 class QWindowsIA2Accessible : public QWindowsMsaaAccessible,
         public IAccessibleAction,
         public IAccessibleComponent,
@@ -258,6 +264,19 @@ private:
 /**************************************************************\
  *                     AccessibleApplication                  *
  **************************************************************/
+
+#ifdef Q_CC_MINGW
+// MinGW's __uuidof operator does not work for the IAccessible2 interfaces
+template <>
+IID qUuidOf<IAccessibleApplication>() { return IID_IAccessibleApplication; }
+
+template <>
+IID qUuidOf<IAccessible2>() { return IID_IAccessible2; }
+
+template <>
+IID qUuidOf<IAccessibleRelation>() { return IID_IAccessibleRelation; }
+#endif // Q_CC_MINGW
+
 class AccessibleApplication : public QWindowsComBase<IAccessibleApplication>
 {
 public:
@@ -277,6 +296,9 @@ public:
 /**************************************************************\
  *                     AccessibleRelation                      *
  **************************************************************/
+
+
+
 class AccessibleRelation : public QWindowsComBase<IAccessibleRelation>
 {
 public:
diff --git a/src/plugins/platforms/windows/accessible/qwindowsaccessibility.cpp b/src/plugins/platforms/windows/accessible/qwindowsaccessibility.cpp
index aed9c94003..e214d47137 100644
--- a/src/plugins/platforms/windows/accessible/qwindowsaccessibility.cpp
+++ b/src/plugins/platforms/windows/accessible/qwindowsaccessibility.cpp
@@ -56,11 +56,7 @@
 #include <QtFontDatabaseSupport/private/qwindowsfontdatabase_p.h> // registry helper
 
 #include "qwindowsaccessibility.h"
-#ifdef Q_CC_MINGW
-#   include "qwindowsmsaaaccessible.h"
-#else
-#   include "iaccessible2.h"
-#endif
+#include "iaccessible2.h"
 #include "comutils.h"
 
 #include <oleacc.h>
@@ -198,11 +194,7 @@ IAccessible *QWindowsAccessibility::wrap(QAccessibleInterface *acc)
     if (!QAccessible::uniqueId(acc))
         QAccessible::registerAccessibleInterface(acc);
 
-# ifdef Q_CC_MINGW
-    QWindowsMsaaAccessible *wacc = new QWindowsMsaaAccessible(acc);
-# else
     QWindowsIA2Accessible *wacc = new QWindowsIA2Accessible(acc);
-# endif
     IAccessible *iacc = 0;
     wacc->QueryInterface(IID_IAccessible, reinterpret_cast<void **>(&iacc));
     return iacc;
diff --git a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
index 308ff59c49..47b179250a 100644
--- a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
+++ b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.cpp
@@ -156,7 +156,7 @@ void accessibleDebugClientCalls_helper(const char* funcName, const QAccessibleIn
 HRESULT STDMETHODCALLTYPE QWindowsMsaaAccessible::QueryInterface(REFIID id, LPVOID *iface)
 {
     *iface = nullptr;
-    const bool result = qWindowsComQueryUnknownInterfaceMulti<AccessibleBase>(this, id, iface)
+    const bool result = qWindowsComQueryUnknownInterfaceMulti<IAccessible2>(this, id, iface)
         || qWindowsComQueryInterface<IDispatch>(this, id, iface)
         || qWindowsComQueryInterface<IAccessible>(this, id, iface)
         || qWindowsComQueryInterface<IOleWindow>(this, id, iface);
@@ -1172,7 +1172,6 @@ const char *QWindowsAccessibleGuid::iidToString(const GUID &id)
         result = "IID_IOleWindow";
     else if (id == IID_IServiceProvider)
         result = "IID_IServiceProvider";
-#ifndef Q_CC_MINGW
     else if (id == IID_IAccessible2)
         result = "IID_IAccessible2";
     else if (id == IID_IAccessibleAction)
@@ -1201,7 +1200,6 @@ const char *QWindowsAccessibleGuid::iidToString(const GUID &id)
         result = "IID_IAccessibleText";
     else if (id == IID_IAccessibleValue)
         result = "IID_IAccessibleValue";
-#endif // !Q_CC_MINGW
     return result;
 }
 
diff --git a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.h b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.h
index 07f10da99a..e654f262da 100644
--- a/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.h
+++ b/src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.h
@@ -46,14 +46,8 @@
 #include <QtCore/qt_windows.h>
 #include <QtCore/qsharedpointer.h>
 #include <QtGui/qaccessible.h>
-#ifndef Q_CC_MINGW
-# include <oleacc.h>
-# include "ia2_api_all.h"   // IAccessible2 inherits from IAccessible
-#else
-    // MinGW
-# include <basetyps.h>
-# include <oleacc.h>
-#endif
+#include <oleacc.h>
+#include "ia2_api_all.h"   // IAccessible2 inherits from IAccessible
 
 QT_BEGIN_NAMESPACE
 
@@ -88,13 +82,7 @@ QDebug operator<<(QDebug d, const QWindowsAccessibleGuid &aguid);
  *                     QWindowsAccessible                     *
  **************************************************************/
 
-#ifndef Q_CC_MINGW
-typedef IAccessible2 AccessibleBase;
-#else
-typedef IAccessible AccessibleBase;
-#endif
-
-class QWindowsMsaaAccessible : public AccessibleBase, public IOleWindow
+class QWindowsMsaaAccessible : public IAccessible2, public IOleWindow
 {
 public:
     QWindowsMsaaAccessible(QAccessibleInterface *a)
diff --git a/src/plugins/platforms/windows/qwindowscombase.h b/src/plugins/platforms/windows/qwindowscombase.h
index f8afcc81cf..5e51b6b7b7 100644
--- a/src/plugins/platforms/windows/qwindowscombase.h
+++ b/src/plugins/platforms/windows/qwindowscombase.h
@@ -46,11 +46,17 @@
 
 QT_BEGIN_NAMESPACE
 
+// The __uuidof operator of MinGW does not work for all interfaces (for example,
+// IAccessible2). Specializations of this function can be provides to work
+// around this.
+template <class DesiredInterface>
+static IID qUuidOf() { return __uuidof(DesiredInterface); }
+
 // Helper for implementing IUnknown::QueryInterface.
 template <class DesiredInterface, class Derived>
 bool qWindowsComQueryInterface(Derived *d, REFIID id, LPVOID *iface)
 {
-    if (id == __uuidof(DesiredInterface)) {
+    if (id == qUuidOf<DesiredInterface>()) {
         *iface = static_cast<DesiredInterface *>(d);
         d->AddRef();
         return true;